1. Field of the Invention
The present invention relates to a light-emitting device with a built-in microlens and a method of forming the same, and more specifically, it relates to a light-emitting device with a built-in microlens having a microlens integrated with a semiconductor light-emitting device and a method of forming the same.
2. Description of the Background Art
In general, a microlens having an aperture of about several 10 μm is known as an optical lens employed for an optical communication system. This microlens is employed in an optical communication system having a transmission medium of optical fiber for efficiently interconnecting optical components such as a semiconductor laser and an optical fiber member with each other.
When such a microlens is assembled with a light-emitting device such as a semiconductor laser, a microlens group manufactured independently of the light-emitting device is generally combined with the light-emitting device thereby obtaining necessary optical properties. When the light-emitting device and the microlens group are manufactured independently of each other, however, the light-emitting device is disadvantageously hard to miniaturize. Further, such combination of the microlens group and the light-emitting device inconveniently requires an optical axis adjusting step with precision of about 1 micron.
Therefore, Japanese Patent Laying-Open No. 2001-28456 or the like generally proposes a technique of forming a microlens integrated with a semiconductor light-emitting device. According to the technique proposed in this gazette, a cladding layer and a contact layer of the semiconductor light-emitting device are partially worked by lithography and etching thereby forming a Fresnel lens pattern (microlens). Thus, a Fresnel lens part (microlens) integrated with the semiconductor light-emitting device is so formed as to require no optical axis adjusting step and enable miniaturization.
In the structure proposed in the aforementioned gazette, however, the microlens is formed by partially working the cladding layer and the contact layer of the semiconductor light-emitting device by lithography and etching, and hence patterning misregistration may be caused in lithography. Such patterning misregistration may disadvantageously result misalignment of an optical axis.